This invention relates to electronic photoflash units used in photography as artificial light sources. More particularly, it relates to computer type electronic photoflash units having adapters which make it possible to use the photoflash units with photographic cameras for each of which an electronic photoflash of a special make and design previously had to be used to the exclusion of other electronic photoflashes.
Electronic photoflashes are becoming almost an indispensable accessory to a photographic camera. Formerly, the function of the electronic photoflash was simply to flash upon reception of a synchronization signal from the camera, and the connection between the camera and the electronic photoflash was used simply for conveying this synchronization signal. However, the functional relation between the camera and the electronic photoflash has become rather complex with the advent of electronic photoflash units as described in U.S. Pat. Nos. 3,033,988 and 3,350,603 sometimes referred to as "computer" type electronic photoflash units. The computer type electronic photoflash is designed for automatically controlling the photoflash light volume as a function of the distance to the object being photographed. The control device is designed to terminate the light flash when the light reflected from the object as measured by a photometric circuit has attained a proper value. With the use of this computer type electronic photoflash, an optimum exposure to a value specified by the computer type electronic photoflash (hereafter referred to as the specified aperture). It is also proposed to provide computer type electronic photoflash units operating at a plurality of specified apertures In this case, a change in the specified aperture requires a corresponding change in the photometric conditions of the computer type electronic photoflash. Therefore, the user is required to set the camera aperture to the prevailing photometric conditions whenever the photometric conditions are changed, a practice often forgotten by the user. It is highly desired that the photometric condition of the computer type electronic photoflash be switched automatically to an optimum one corresponding to the camera aperture setting or that, conversely, the camera aperture be set to a proper value corresponding to the specified aperture of the computer type electronic photoflash. Moreover, since modern cameras often include photometric circuits themselves, if the photometric circuit of the camera is to be used for controlling the photoflash light volume of the computer type electronic photoflash, there is no necessity of changing the photometric conditions of the computer type electronic photoflash. To this end, the computer type electronic photoflash and the camera must be combined organically to each other.
Combinations of computer type electronic photoflash units and cameras capable of automatically making the desired adjustments as described have been proposed in the art and are presently available on the market. The electronic photoflash units for use in such combinations are often referred to as "dedicated" units. However, the manners in which the cameras and the photoflash units are combined are often different for different cameras and for cameras of different manufacturers. The situation has arisen where different ones of the different major camera manufacturers have marketed cameras having different schemes for combining their cameras and photoflash units. Each different scheme results in a camera which either supplies to or requires from the photoflash unit different combinations of electrical signals representing different parameters. Thus, users who own cameras of different manufacturers making use of different combination schemes have in the past been required to purchase different flash units for each of the cameras. Moreover, photoflash manufacturers who desire the supply units useful with cameras of many different manufacturers have in the past faced the prospect of supplying different units for each scheme of combination, a practice which is rather uneconomical. Thus, it has become desirable to provide apparatus by which a single photoflash unit may be used in common with cameras making use of various different interconnection schemes between the camera and the photoflash unit.